It is a great thread, and discussion. The cosmos has always fascinated me, and the comments here have and are most enjoyable, on a topic that even the most qualified are sometimes at odds with how it all began, and where it it is going.

Is it possible the universe is both expanding and collapsing, depending on where you are?

Like the original question. We're using data to determine remote life that is arguably older than our own civilization., and we're learning new things every day..... including more about what we don't know.

turnin: Our universe is expanding but also accelerating (which does not line up with our thinking about a singular big bang which would not accelerate matter after the fact). So I wonder if we are not being pulled by a force other than gravity. Perhaps if we are only seeing the old light, perhaps we are being dragged by a force that no longer exists also ?

if you push something in a vacuum at an constant rate it will speed up you just have to remember that the initial outward force of the big bangs shock wave is still travelling outward

That's not it (shock wave).Whatever is making the rate of expansion accelerate (if that is actually what is happening) is also having to counter the always attractive force of gravity - which should be slowing it down.A hypothesis is that it could be "dark energy" - the cosmological constant proposed by Einstein (to explain an apparently incorrect assumption believed at the time) - then abandoned by him as his "greatest blunder" but which might not have been a blunder at all ...

joker97: Dude if you travel at light speed time stops completely. So you can go however far you want and not grow old and never have to pee or eat.

Perhaps even go back in time.

Sorry but I don't think it does. Things are relative to the event that caused them - when an event occurs - time starts at the event and travels outwards away from it - that is called an event horizon. Anything outside of that horizon is not affected by the event because it hasn't happened yet.

If we assume that the universe is closed (like a sphere) then everything outside of the universe is not affected by anything inside it. The edge of the observable universe is about 46 billion light years away (according to Wikipedia) but the edge of the universe I guess is unknown - if they can detect and measure gravitational waves then we might be able to learn more about it.

TwoSeven: The edge of the observable universe is about 46 billion light years away (according to Wikipedia)

It's not quite that simple...The most distant object observed, the light we observe that came from it, came from a distance of about 13 billion light years, but we and the object have moved further apart since then, so project it's position "now" from observed rate of expansion, allow for acceleration of the rate of expansion, and allow for the observed age of the object (which formed after the big bang - so the expanded universe extends beyond the calculated position of that object).Then you come up with a figure which may or may not be right and a concept of where it (the object and the even further "edge of the universe") is "now" in spacetime, when the object or place in that "now" may probably have already passed the event horizon and has (from our relative position) already departed the universe - and in any meaningful sense, no longer exists.

josephhinvest: There's a very good image on Wikipedia that attempts to show the scale of the universe. I think that with all things being equal, life will have arisen independently millions of times throughout the universe. I don't think our little planet is particularly special.

josephhinvest: There's a very good image on Wikipedia that attempts to show the scale of the universe. I think that with all things being equal, life will have arisen independently millions of times throughout the universe. I don't think our little planet is particularly special.

josephhinvest: There's a very good image on Wikipedia that attempts to show the scale of the universe. I think that with all things being equal, life will have arisen independently millions of times throughout the universe. I don't think our little planet is particularly special.

Cheers, Joseph

Mind. Officially. Blown.

These images blow my mind:

Take a very small slice of empty sky called XDF (shown left) - look at it using the Hubble telescope (right):

josephhinvest: There's a very good image on Wikipedia that attempts to show the scale of the universe. I think that with all things being equal, life will have arisen independently millions of times throughout the universe. I don't think our little planet is particularly special.

Cheers, Joseph

Mind. Officially. Blown.

These images blow my mind:

Take a very small slice of empty sky called XDF (shown left) - look at it using the Hubble telescope (right):

Very cool.

The events it has photographed occurred a loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong time ago, that region would look completely different now

MikeRetired IT Manager, Freelance money spenderThe views stated in my posts are my personal views and not that of any other organisation.

Being in pain does not necessarily ruin your life, it does however remind you that you are still alive.

My two cents' worth on all this is that we (OK, "they" - I'm not involved in this) are discovering new planets orbiting stars all the time, and a few of these are in the goldilocks zone, which means there is a chance some of those planets may support life as we know it. So add to what has been observed, and allow for the ones they haven't discovered yet, and add to that the possiblity of planets outside of the goldilocks zone supporting life that is very different from life on Earth. All in all, I'd be very surprised if there wasn't life out there somewhere.

Of course, that doesn't mean that I think they have visited us and left their mark on ancient civilisations or are killing cattle or abducting people and implanting chips into the backs of our necks...

joker97: forgot to add. if anyone wants concrete layperson explanations on theoretical physics head straight to the library and get a book called

The Beginning of Time by Stephen Hawkings

I know Hawking did a lecture called The Beginning of Time in the late 1990s but I think the book you are referring to is A Brief History of Time. Of more relevance to this thread is his lecture called Life in the Universe.